1. Field of the Invention
The invention relates to an apparatus for dissolving gas in liquid, and more particularly to an apparatus for venting a bubble contactor employed to dissolve gas in liquid.
2. Reference to Prior Art
In many processes it is desirable to dissolve gasses in liquids. In one such process an apparatus for dissolving oxygen in water is employed in a water treatment system for removing fuel constituents from water contaminated thereby. The apparatus for dissolving oxygen in water, or "oxygenator", includes a bubble contactor having a degas vessel and a downwardly diverging member extending into the degas vessel for conducting a downflow of water into the degas vessel. The downwardly diverging member defines a bubble contact zone in which oxygen containing bubbles tend to suspend. Excess gas bubbles crowded out of the bubble contact zone escape from the bottom of the downwardly diverging member and ascend to a gas trap at the top of the degas vessel. By routing the gas bubbles in this manner their entry into the outlet of the bubble contactor located near the bottom of the degas vessel is avoided. However, a disadvantage associated with the aforementioned bubble contactor is the complexity of its design.
The oxygenator is also provided with a gas vent system communicating with the gas trap. The vent systems, if left open, results in a continuous gas loss that can be costly since oxygen enriched gases are expensive to produce If the vent system is left closed, excess gas bubbles can accumulate to the extent that they are transferred through the bubble contactor outlet to a downstream fluid bed reactor where they can degrade reactor performance.
Additional examples of oxygenators including gas venting arrangements are provided in U.S. Pat. No. 4,477,393 issued Oct. 16, 1984 to Kos and U.S. Pat. No. 3,926,588 issued Dec. 16, 1975 to Speece. The venting arrangements employed in these examples continually vent gas, resulting in waste of oxygen.